Field of the Invention
The present invention relates to a drive device that drives a pixel region of a liquid crystal panel and to a liquid crystal display apparatus that includes the drive device.
Description of the Background Art
The use of the same part in liquid crystal display apparatuses of different sizes has led to a reduced cost (a unit cost of the part) by increased purchases of the same part or to “platform” for reducing a period of development and design resources. The same common part has been used in various kinds of liquid crystal panels.
A high-resolution and large liquid crystal display apparatus typically tends to cause a heavy load connected to an output stage of a driver integrated circuit (IC) that drives a liquid crystal panel. The driver IC includes a circuit capable of driving a liquid crystal panel even under heavy load conditions. In one example, some driver ICs capable of driving a liquid crystal panel under heavy load conditions include an assist circuit (auxiliary circuit) that assists (supports) an output from an output amplifier for cases where sufficient output cannot be obtained only by driving capability of the output amplifier.
Some applications of a liquid crystal display require low power consumption, and many attempts have been made to minimize a load on a liquid crystal panel. Some liquid crystal panels have a structure having a reduced capacity or a reduced resistance of source lines (for example, see Japanese Patent Application Laid-Open No. 5-41651 (1993) and Japanese Patent Application Laid-Open No. 2001-255857). In consideration of the platform and the drive of various kinds of liquid crystal panels under load conditions, the driver IC capable of driving a liquid crystal panel under heavy load conditions is eventually used to drive a liquid crystal panel under low load conditions in some cases.
The conventional assist circuit has no problem in operating under originally assumed heavy load conditions, but may generate a flow-through current at a low load depending on conditions. An increase in the flow-through current does not affect a display. Thus, whether the flow-through current is generated cannot be easily monitored according to product conditions, thereby making it difficult to determine whether the liquid crystal panel is under abnormal conditions.